54
the open sun drying method, the economic costs of dried peeled shrimp have been
proven to be better than the sun dried method for solar tunnel dryer (Manjarekar and
Mohode 2010).
In the tropical and subtropical regions, various types of solar dryers have been
designed and developed for drying seafood. The solar energy dryers are distinguished in two main categories. These are natural convection, so-called passive dryers, and forced convection called active dryer. In active dryers, the air velocity is
higher, and the drying time is shorter. In addition to all these, passive dryers require
less investment costs and operate more simply (Nguyen et al. 2014).
In a study examining the properties of dried shrimps dried in a combined solar
drying with low humidity air, the shrimps were dried in a daytime solar energy dryer
(greenhouse dryer) and then dried in an air-conditioned controlled system overnight. At night, the low temperature and low relative humidity drying system kept
the temperature between 28 and 30 °C for shrimp drying and relative humidity to
40–45% Rh. It has been determined that the products take 16 h to dry in this system
(Wisaiproma et al. 2018).
Heat Pumping Drying
The heat pump is an effective device that removes thermal energy from a lower
temperature source and leaves it to a higher temperature source. A heat pump drier
is more costly than hot air drying, as it can extract and use the latent energy of air
and water vapour to dry the product. However, it is a useful method for drying valuable and sensitive products such as shrimp due to its low temperature drying capability. Because the heat pump uses less energy, it offers an effective and
environmentally friendly technology (Strømmen et al. 2000).
In a study in which peeled, headed or whole shrimp (Pandalus borealis) were
dried in a heat pump drier at a temperature of −2 to 0 °C to 20 °C respectively, and
the desorption isotherms of each shrimp sample group were characterized, drying
rate of headed shrimp was found higher than that of whole shrimp (Guochen
et al. 2009).
Freeze Drying
The freeze-drying method is also called lyophilisation. Freeze drying generally consists of two steps: (1) the product is frozen; (2) the product is dried by direct sublimation. Freeze drying is expensive, but in terms of quality it is the best drying
method. Preserving the appearance, taste, colour, taste, structure of the raw material
makes it the best drying method. The product also has good rehydration properties
as it retains its initial shape and size. Very good preservation of aroma and flavour,
high preservation of nutritional value, minimum shrinkage, and minimal change in
shape, colour and appearance, negligible effect on structure and texture, and good
rehydration properties due to the porosity of the final structure are the advantages of
freezing drying (Aguilera et al. 2003). Also, as the water is about 98% removed, the
weight of the product is reduced, which reduces the transport and storage costs.
2 Crustacean Shellfish
the open sun drying method, the economic costs of dried peeled shrimp have been
proven to be better than the sun dried method for solar tunnel dryer (Manjarekar and
Mohode 2010).
In the tropical and subtropical regions, various types of solar dryers have been
designed and developed for drying seafood. The solar energy dryers are distinguished in two main categories. These are natural convection, so-called passive dryers, and forced convection called active dryer. In active dryers, the air velocity is
higher, and the drying time is shorter. In addition to all these, passive dryers require
less investment costs and operate more simply (Nguyen et al. 2014).
In a study examining the properties of dried shrimps dried in a combined solar
drying with low humidity air, the shrimps were dried in a daytime solar energy dryer
(greenhouse dryer) and then dried in an air-conditioned controlled system overnight. At night, the low temperature and low relative humidity drying system kept
the temperature between 28 and 30 °C for shrimp drying and relative humidity to
40–45% Rh. It has been determined that the products take 16 h to dry in this system
(Wisaiproma et al. 2018).
Heat Pumping Drying
The heat pump is an effective device that removes thermal energy from a lower
temperature source and leaves it to a higher temperature source. A heat pump drier
is more costly than hot air drying, as it can extract and use the latent energy of air
and water vapour to dry the product. However, it is a useful method for drying valuable and sensitive products such as shrimp due to its low temperature drying capability. Because the heat pump uses less energy, it offers an effective and
environmentally friendly technology (Strømmen et al. 2000).
In a study in which peeled, headed or whole shrimp (Pandalus borealis) were
dried in a heat pump drier at a temperature of −2 to 0 °C to 20 °C respectively, and
the desorption isotherms of each shrimp sample group were characterized, drying
rate of headed shrimp was found higher than that of whole shrimp (Guochen
et al. 2009).
Freeze Drying
The freeze-drying method is also called lyophilisation. Freeze drying generally consists of two steps: (1) the product is frozen; (2) the product is dried by direct sublimation. Freeze drying is expensive, but in terms of quality it is the best drying
method. Preserving the appearance, taste, colour, taste, structure of the raw material
makes it the best drying method. The product also has good rehydration properties
as it retains its initial shape and size. Very good preservation of aroma and flavour,
high preservation of nutritional value, minimum shrinkage, and minimal change in
shape, colour and appearance, negligible effect on structure and texture, and good
rehydration properties due to the porosity of the final structure are the advantages of
freezing drying (Aguilera et al. 2003). Also, as the water is about 98% removed, the
weight of the product is reduced, which reduces the transport and storage costs.
2 Crustacean Shellfish